符号变量替换：Python

Question

我希望通过代入符号变量'x'的值来找到给定方程的值。但是，输出仍然包含变量：

import math
from sympy import *

m = var ('x')
x = m
i = 1

while i <= 100:
    m = sin(m)
    i = i + 1

i = 1

while i <= 7:
    k = diff(m,x)
    i = i + 1

print(k.subs(x, 0))  

输出：

cos(x)*cos(sin(x))*cos(sin(sin(x)))*cos(sin(sin(sin(x))))*cos(sin(sin(sin(sin(x)))))*cos(sin(sin(sin(sin(sin(x))))))*cos(sin(sin(sin(sin(sin(sin(x)))))))*cos(sin(sin(sin(sin(sin(sin(sin(x))))))))*cos(sin(sin(sin(sin(sin(sin(sin(sin(x)))))))))*cos(sin(sin(sin(sin(sin(sin(sin(sin(sin(x))))))))))

先谢谢您！

Answer 1

根据标题进行回答，使用

k.evalf(subs={x: 0})

但是我真的认为您应该处理您的代码。它不是Pythonic，可能无法满足您的目的。